- Enantioselective Direct Alkynylation of Ketones Catalyzed by Chiral CCN Pincer RhIIIComplexes
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A direct asymmetric alkynylation of ketones with new chiral CCN Rh catalysts containing N-heterocyclic carbene and oxazoline hybrid ligands is described. The catalytic reaction of fluoroalkyl-substituted ketones, ArCOCF2X (X=F, Cl, H), with aromatic and aliphatic alkynes yielded the corresponding chiral propargyl alcohols with high enantioselectivity. Control and kinetic experiments suggested a bis(alkynyl) Rh intermediate as the active species for the C?C bond-forming step.
- Ito, Jun-Ichi,Ubukata, Shino,Muraoka, Shun,Nishiyama, Hisao
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Read Online
- Cu(OAc)2-porphyrins as an efficient catalytic system for base-free, nature mimicking Chan–Lam coupling in water
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The use of porphyrins as ligands in organic synthesis reveals the natural process, because these are the constituent motifs of catalysts in many bio-organic reactions. This article presents the synthesis of two N-pincer tetradentate porphyrins; tetrasodium meso-tetra(p-sulfonatophenyl)phorphyrin (H2TSTpSPP) and meso-tetra(m-carboxyphenyl)porphyrin (H2TmCPP), and study on their aptness for Cu-catalyzed C–N coupling reactions of arylboronic acids and amines (Chan–Lam coupling reaction) in water under external base free conditions. The porphyrins and Chan–Lam coupling products were well characterized by their spectral analysis. The high product yields, application of nature-inspired conditions, large extent of substrates, ease of making and handling the ligands, avoidance of base, and use of water as reaction media are the attractive attributes of this finding.
- Venkateswarlu, Katta,Rao, Kanusu Umamaheswara
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- Steric effects on acetate-assisted cyclometallation ofmeta-substitutedN-phenyl andN-benzyl imidazolium salts at [MCl2Cp*]2(M = Ir, Rh)
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meta-SubstitutedN-phenyl,N′-methyl andN-benzyl,N′-methyl imidazolium salts undergo acetate-assisted cyclometallation to provide mixtures oforthoandparasubstituted cyclometallated complexes. The effect of the substituents on the isomer ratios is discussed; steric effects are more important in the 6-membered rings derived from theN-benzyl imidazolium salts than 5-membered rings from theN-phenyl salts. Comparisons are made to steric effects with some other common directing groups.
- Davies, David L.,Singh, Kuldip,Tamosiunaite, Neringa
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p. 13505 - 13515
(2021/10/12)
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- High-performance sono/nano-catalytic system: CTSN/Fe3O4-Cu nanocomposite, a promising heterogeneous catalyst for the synthesis of: N -arylimidazoles
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Herein, a promising heterogeneous nanoscale catalytic system constructed of chitosan (CTSN, as a polymeric basis), iron oxide nanoparticles (Fe3O4 NPs, as the magnetic agent), and copper oxide nanoparticles (CuO NPs, as the main cata
- Taheri-Ledari, Reza,Hashemi, Seyed Masoud,Maleki, Ali
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p. 40348 - 40356
(2019/12/25)
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- Framework-Copper-Catalyzed C?N Cross-Coupling of Arylboronic Acids with Imidazole: Convenient and Ligand-Free Synthesis of N-Arylimidazoles
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A convenient and environmentally benign synthesis of N-arylimidazoles has been demonstrated by a straightforward reaction catalyzed by the unsaturated coordination sites of Cu in the copper terephthalate metal–organic framework (Cu(tpa)-MOF). A series of N-arylimidazoles has been synthesized in excellent yields by the C?N cross-coupling reaction of arylboronic acids and imidazoles catalyzed by the Cu(tpa)-MOF using ethanol as a benign solvent. The present ligand-free catalytic system proceeds smoothly under mild conditions, avoids stoichiometric Cu reagents, tolerates many functional groups, has a wide substrate scope, and is feasible with other nitrogen heterocycles. The stability and heterogeneity of the catalyst is evidenced by the results of a heterogeneity test, and the catalyst can be reused several times without a loss of activity. The easy preparation of the catalyst, its stability, recovery by simple filtration, and reusability reveal Cu(tpa) MOF as a versatile catalyst for academic and industrial applications.
- Devarajan, Nainamalai,Suresh, Palaniswamy
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p. 2953 - 2960
(2016/09/28)
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- Mild transition-metal-free amination of fluoroarenes catalyzed by fluoride ions
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Trimethylsilyl-protected heterocycles undergo N-C bond formation with a variety of electron-deficient fluoroarenes catalyzed by fluoride ions. This reaction avoids stoichiometric amounts of base and thus makes N-arylheterocycles accessible in a very mild and transition-metal-free way.
- Dehe, Daniel,Munstein, Isabel,Reis, Andreas,Thiel, Werner R.
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experimental part
p. 1151 - 1154
(2011/05/02)
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- Coordination polymers of various architectures built with mixed imidazole/benzimidazole and carboxylate donor ligands and different metal ions: Syntheses, structural features and magnetic properties
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Ten coordination polymers {[Cd(L1)2]}n (1), {[Cu(L1)2]}n (2), {[Cd2(L 1)2(HCOO)2(H2O)]}n (3), {[Cd2(L1/sub
- Aijaz, Arshad,Lama, Prem,Sanudo, E. Carolina,Mishra, Rupali,Bharadwaj, Parimal K.
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experimental part
p. 2502 - 2514
(2011/01/11)
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- Copper-catalyzed C-N coupling of amides and nitrogen-containing heterocycles in the presence of cesium fluoride
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The copper-catalyzed C-N coupling of amides to aryl halides usually requires the use of strong alkali metal bases, such as K2CO3, K3PO4, and Cs2CO3, at high temperature. We discovered that
- Phillips, Dean P.,Zhu, Xue-Feng,Lau, Thomas L.,He, Xiaohui,Yang, Kunyong,Liu, Hong
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supporting information; experimental part
p. 7293 - 7296
(2010/03/03)
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- NITROGEN CONTAINING HETEROAROMATICS AS FACTOR Xa INHIBITORS
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The present application describes nitrogen containing heteroaromatics and derivatives thereof of formula (I) or pharmaceutically acceptable salt or prodrug forms thereof, wherein J is N or NH and D may be C(=NH)NH2, which are useful as inhibitors of factor Xa.
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Page/Page column 34
(2009/10/01)
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- Per-6-amino-β-cyclodextrin as an efficient supramolecular ligand and host for Cu(I)-catalyzed N-arylation of imidazole with aryl bromides
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(Chemical Presented) Per-6-amino-β-cyclodextrin (per-6-ABCD), acting simultaneously as a supramolecular ligand for CuI and host for aryl bromides, catalyzes N-arylation of imidazole with aryl bromides under mild conditions. This simple method proceeds with excellent yield for the coupling of imidazole with various substituted aryl bromides demonstrating good tolerance of other functionalities.
- Suresh, Palaniswamy,Pitchumani, Kasi
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experimental part
p. 9121 - 9124
(2009/04/11)
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- Copper-catalyzed N-arylation of imidazoles and benzimidazoles
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(Chemical Equation Presented) 4,7-Dimethoxy-1,10-phenanthroline (L1c) was found to be an efficient ligand for the copper-catalyzed N-arylation of imidazoles and benzimidazoles with both aryl iodides and bromides under mild conditions. Further optimization of the system has revealed that the addition of poly(ethylene glycol) accelerates this reaction. A variety of hindered and functionalized imidazoles, benzimidazoles, and aryl halides were transformed in good to excellent yields. Heteroaryl halides were also coupled in moderate to good yields. We also present the results obtained from a series of coupling reactions, which directly compare the use of L1c with other recently reported ligands.
- Altman, Ryan A.,Koval, Erica D.,Buchwald, Stephen L.
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p. 6190 - 6199
(2008/02/10)
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- An Ullmann coupling of aryl iodides and amines using an air-stable diazaphospholane ligand
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(Chemical Equation Presented) A copper-based catalytic system, using an air-stable diazaphospholane as the ligand, was developed for an efficient Ullmann reaction between aryl iodides and alkyl or heterocyclic amines.
- Yang, Minghua,Liu, Fei
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p. 8969 - 8971
(2008/03/27)
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- 4,7-Dimethoxy-1,10-phenanthroline: An excellent ligand for the Cu-catalyzed N-arylation of imidazoles
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4,7-Dimethoxy-1,10-phenanthroline (L) was found to be an efficient ligand for the copper-catalyzed N-arylation of imidazole with aryl iodides and bromides under mild conditions. A variety of hindered and functionalized imidazoles and aryl halides were transformed in good to excellent yields.
- Altman, Ryan A.,Buchwald, Stephen L.
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p. 2779 - 2782
(2007/10/03)
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- Synthesis and SAR of benzamidine factor Xa inhibitors containing a vicinally-substituted heterocyclic core
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The selective inhibition of coagulation factor Xa has emerged as an attractive strategy for the discovery of novel antithrombotic agents. Here we describe highly potent benzamidine factor Xa inhibitors based on a vicinally-substituted, heterocyclic core.
- Fevig, John M.,Pinto, Donald J.,Han, Qi,Quan, Mimi L.,Pruitt, James R.,Jacobson, Irina C.,Galemmo, Jr, Robert A.,Wang, Shuaige,Orwat, Michael J.,Bostrom, Lori L.,Knabb, Robert M.,Wong, Pancras C.,Lam, Patrick Y.S.,Wexler, Ruth R.
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p. 641 - 645
(2007/10/03)
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- Nitrogen containing heteroaromatics as factor Xa inhibitors
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The present application describes nitrogen containing heteroaromatics and derivatives thereof of formula I: or pharmaceutically acceptable salt or prodrug forms thereof, wherein J is N or NH and D may be C(=NH)NH2, which are useful as inhibitors of factor Xa.
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- 6-aryl pyrazolo?3,4-D! pyrimidin-4-ones and compositions and method of use thereof
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6-Aryl pyrazolo?3,4-d!pyrimidin-4-one derivatives, pharmaceutical compositions containing them and methods for effecting c-GMP-phosphodiesterase inhibition and for treating heart failure and/or hypertension.
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